The present invention relates to a color filter and method of fabricating the same, and more particularly to a color filter having a bi-layer metal grating.
Color filter, a main component in an LCD device, converts white light to red, green, and blue light. Methods of fabrication comprise dyeing, printing, electrodeposition, or pigment dispersal. Pigment dispersal and dyeing methods are both popularly used.
FIG. 1 shows a pigment dispersed method, comprising coating of photoresist, pre-baking, exposure, development, and post-baking. A color array, including red, green, and blue films, is formed by repeating the steps three times. The red, green, and blue films have different thicknesses to achieve agreement of light intensity. In addition to being complex and low yield, the method is also limited by low color saturation, non-uniform thickness.
As well, Dyeing offers only low resistant to heat and chemicals. Nether method significantly improves color purity.
For a color filter, optical properties, compatibility with subsequent process, and reliability are all priorities, with optical properties such as transmission and color saturation being most important.
High transmission requires less intensity from backlight, thereby saving power. Red, green, and blue transmittance percentages are required to approach 85%, 75%, and 75%, respectively.
High color saturation can be achieved by coupling a color filter with a backlight. The backlight may be a cold cathode fluorescent lamp. FIG. 2 is a chart showing the transmission spectrum for a cold cathode fluorescent lamp. However, as shown in FIG. 2, there are two undesired transmission peaks at 490 nm and 580 nm, resulting in a significant loss of color saturation. In addition, a conventional color filter, as shown in FIG. 3, can't effectively eliminate the described transmitted light.
Accordingly, a simplified method for fabricating a color filter capable of enhancing color saturation is required.